Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se-Se bond in 2-(Me₂NCH₂)C₆H₄]₂Se₂ (1) was achieved by treatment with SO₂Cl₂ (1:1 molar ratio) or elemental halogens to yield 2-(Me₂NCH₂)C₆H₄]SeX X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO₂Cl₂ (1:3 molar ratio) gave 2-(Me₂NCH₂)C₆H₄]SeCl₃ (5). 2-(Me₂NCH₂)C₆H₄]SeS(S)CNR₂ R = Me (6), Et (7)] were prepared by reacting 2-(Me₂NCH₂)C₆H₄]SeBr with NaS₂CNR₂] · nH₂O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K(SPMe₂)(SPPh₂)N] resulted in isolation of 2-(Me₂NCH₂)C₆H₄]Se-S-PMe₂N-PPh₂S (8). The compounds were characterized by solution NMR spectroscopy (¹H, ¹³C, ³¹P, ⁷⁷Se, 2D experiments). The solid-state molecular structures of 2, 4-8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH₂NMe₂ arm involved in a three-center-four-electron N?Se-X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6-8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se?Cl interactions (3.40 Å); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals.